Cyanotype is a photographic printing process that produces a cyan-blue print. Engineers used the process well into the 20th century as a simple and low-cost process to produce copies of drawings, blueprints.
The process uses two chemicals, mixes in equal parts: ammonium iron(III) citrate [20% solution] and potassium ferricyanide [8.1% (w/v) solution]. These are available at art supply stores, photography stores and, of course, online. Only mix enough to use during a single session, as it only keeps for about 3-4 hours. Apply to a surface with a brush. I used a foam brush.
The solution can be applied to any porous surface, including paper (especially watercolor paper), cloth, canvas and even drywall. Allow to dry completely before applying second or third coats. I found that one is probably enough. Once the paper is dry, keep it in a dark place, such as a black plastic contractor bag.
I printed some digital negatives of two Delft China patterns and one of my dioramas onto a piece of 8×11 transparency film. I also copied a postcard about a shoe art exhibit onto a transparent sheet in a photo copier.
I put the transparent negatives, along with a feather, in a window box and placed it in the sun for about 9 minutes.
It was a very bright day. The paper gradually changed colors, turning a silvery brown.
I also tried this with my hand, as objects can be laid on the paper, too.
I rinsed the paper in warm water for about 7 minutes or so – just long enough to see the white highlights show through the blue. The process stops as soon as the paper is submerged. If the paper seems yellow after drying, it can be rinsed again. I started in the big blue baby pool to get most of the solution off, then used the other two boxes.
The photo above shows four of my attempts at this process – the feather image has one coat of the solution, the hand and shoes have two coats, and the big piece has three coats.
It was really simple – I plan to do more of these.
If YOU are interested, you should check out Gray Lyons beautiful work. She showed me how to do this, and she was as kind as she is talented.